Inter-AS Option B between Juniper routers

Recently I stumbled on a topic related to interconnecting 2 Juniper routers with Inter-AS Option B.

With this kind of connectivity it is not enough to have control plane working properly i.e. prefixes exchanged and visible in appropriate routing-instances on both ends – for data plane to work you need to have next-hop resolved – and it is implicit in case E-BGP peering is sourced with interface address. In case loopback is used as a source you need to have it resolved by:

More details can be found on the Juniper forum where I found the solution.

There are also 2 useful commands that can be used for troubleshooting next-hop connectivity

show krt indirect-next-hop
show route <prefix> extensive